class_docstr: A subgraph of a TensorFlow computational graph.
  
  TensorFlow graphs are often too low-level to represent our conceptual
  understanding of a model
  
  OverlayGraph can be used to represent a simplified version of a TensorFlow
  graph. Each node corresponds to a node in the original TensorFlow graph, and
  edges correspond to paths through the original graph.
docstr: Print graphviz graph.
docstr_tok: ["Print","graphviz","graph","."]
code: def graphviz(self, groups=None):
      """Print graphviz graph."""
  
      print("digraph G {")
      if groups is not None:
          for root, group in groups.items():
              print("")
              print(
                  (
                      "  subgraph",
                      "cluster_%s" % root.name.replace("/", "_"),
                      "{",
                  )
              )
              print(('  label = "%s"') % (root.name))
              for node in group:
                  print(('    "%s"') % node.name)
              print("  }")
      for node in self.nodes:
          for inp in node.inputs:
              print(
                  "  ",
                  '"' + inp.name + '"',
                  " -> ",
                  '"' + (node.name) + '"',
              )
      print("}")
  
imports: from collections import defaultdict
  import numpy
  import tensorflow
label_desc: Use image node_id 6 for calling the OverlayGraph obj's underlying member method code with example usage: obj.graphviz(groups) without return types